Bispecific anti-Cmet/anti-Her2 antibodies

ABSTRACT

There are provided an anti-c-Met/anti-Her2 bispecific antibody, and a method for preventing and/or treating cancer using the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2013-0033876 filed on Mar. 28, 2013, in the Korean Intellectual Property Office, the entire disclosure of which is herein incorporated by reference.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ELECTRONICALLY

Incorporated by reference in its entirety herein is a computer-readable nucleotide/amino acid sequence listing submitted concurrently herewith and identified as follows: One 142,361 Byte ASCII (Text) file named 715709_ST25-Revised3 created on Jun. 12, 2017.

BACKGROUND OF THE INVENTION 1. Field

Provided are an anti-c-Met/anti-Her2 bispecific antibody, and a method for preventing and/or treating cancer using the same.

2. Description of the Related Art

c-Met and Her2 (or HER family) proteins interact with each other and are involved in various mechanisms related to tumors. These proteins are typical receptor tyrosine kinases (RTKs) present at the surface of cells, and thus, they induce the proliferation of cancer cells, the penetration of the cancer cells, angiogenesis, etc. Also, these proteins participate in each other's signal transduction system by interacting with each other, thereby inducing resistance against each other's therapeutic agents.

Meanwhile, multispecific antibodies targeting two or more antigens have been developed in various kinds and forms and are expected as a new drug antibody having excellent therapeutic effects compared to a monoclonal antibody. Most multispecific antibodies have been developed so that their therapeutic effects on cancers can be increased by recognizing an antigen of cytotoxic cells (killer cells) and another antigen of cancer cells at the same time, thereby allowing the cancer cells to be killed by the cytotoxic cells. Research results reveal that cancer cells themselves can be mutated to proliferate and penetrate by intracellular ligands or various antigens of the same cancer cells other than the targeted antigen. Therefore, there is a desire to develop a multispecific antibody capable of recognizing another antigen of the cancer cells, as well as an antigen of the killer cells, for treating cancers.

BRIEF SUMMARY OF THE INVENTION

One embodiment provides an anti-c-Met/anti-Her2 bispecific antibody including (a) an anti-c-Met antibody or an antigen-binding fragment thereof and (b) an anti-Her2 antibody or an antigen-binding fragment thereof, wherein the anti-c-Met antibody is an antibody specifically binding to an epitope consisting of consecutive 5 or more amino acids within a SEMA domain (SEQ ID NO: 79) of c-Met protein, wherein the epitope comprises at least the amino acid sequence of SEQ ID NO: 73.

Another embodiment provides a pharmaceutical composition for preventing and/or treating cancer including the anti-c-Met/anti-Her2 bispecific antibody as an active ingredient.

Another embodiment provides a method for preventing and/or treating cancer, including administering a pharmaceutically effective amount of the anti-c-Met/anti-Her2 bispecific antibody to a patient in need of the prevention and treatment of cancer.

Still another embodiment provides a use of the anti-c-Met/anti-Her2 bispecific antibody for the prevention and/or treatment of cancer.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

FIG. 1 is a schematic diagram showing the structure of an anti-c-Met/anti-Her2 bispecific antibody according to one example.

FIG. 2 is a graph showing dual binding of an anti-c-Met/anti-Her2 bispecific antibody according to one example. Binding response differential (Ru) is indicated on the y-axis, and time (seconds) is indicated on the x-axis.

FIG. 3 contains graphs showing proliferation levels of cancer cells (MKN45 stomach cancer cell line (upper) and EBC-1 lung cancer cell line (lower)) when treated with an anti-c-Met/anti-Her2 bispecific antibody according to one example as relative values against the control group (Medium; antibody non-treatment group).

FIG. 4 contains western blotting results showing Her2 activation inhibitory degrees of an anti-c-Met/anti-Her2 bispecific antibody according to one example in a MKN45 stomach cancer cell line (upper) and EBC-1 lung cancer cell line (lower).

FIG. 5 contains confocal microscope photographs showing the co-localization of cMet and Her2 in a MKN45 stomach cancer cell line by an anti-c-Met/anti-Her2 bispecific antibody according to one example.

FIG. 6 contains confocal microscope photographs showing the co-localization of cMet and Her2 in an EBC-1 lung cancer cell line by an anti-c-Met/anti-Her2 bispecific antibody according to one example.

FIG. 7 contains confocal microscope photographs showing the co-localization of cMet and Her2 in an OE-33 esophagus cancer cell line by an anti-c-Met/anti-Her2 bispecific antibody according to one example.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of the present invention provides an anti-c-Met/anti-Her2 bispecific antibody comprising, consisting essentially of, or consisting of (a) an anti-c-Met antibody or an antigen-binding fragment thereof, and (b) an anti-Her2 antibody or an antigen-binding fragment thereof.

The antigen-binding fragment may be selected from the group consisting of scFv, (scFv)2, Fab, Fab′, and F(ab′)2.

The “c-Met protein” refers to a receptor tyrosine kinase binding to hepatocyte growth factor. The c-Met proteins may be derived from any species, for example, those derived from primates such as human c-Met (e.g., NP_000236) and monkey c-Met (e.g., Macaca mulatta, NP_001162100), or those derived from rodents such as mouse c-Met (e.g., NP_032617.2) and rat c-Met (e.g., NP_113705.1). The proteins include, for example, a polypeptide encoded by the nucleotide sequence deposited under GenBank Accession Number NM_000245, or a protein encoded by the polypeptide sequence deposited under GenBank Accession Number NM_000236, or extracellular domains thereof. The receptor tyrosine kinase c-Met is involved in several mechanisms including cancer incidence, cancer metastasis, cancer cell migration, cancer cell penetration, angiogenesis, etc.

The “Her2 (human epidermal growth factor receptor 2)” is encoded by ERBB2 gene, and is a member of the epidermal growth factor receptor (EGFR/ErbB). Her2 has been known to play an essential role in regulating cell proliferation and differentiation. Particularly, when bound to extracellular growth factors, it has a strong tendency of being assembled into homo- and/or heterodimers along with other HER receptors, which results in the activation of several forms of signal transduction pathway and induces apoptosis, survival, or cell proliferation.

For instance, the Her2 proteins may be polypeptides encoded by the nucleotide sequences (mRNA) deposited under GenBank Accession Number NM_004448.2, NM NM_001005862.1, etc.

In one embodiment, the anti-Her2 antibody may be selected from the group consisting of Trastuzumab, Pertuzumab, and Trastuzumab emtansine (T-DM1).

The antigen binding site of the anti-Her2 antibody recognizing Her2 as an antigen may be an antigen binding site, for example, scFv, (scFv)₂, Fab, Fab′ or F(ab′)2 of an anti-Her2 antibody selected from the group consisting of Trastuzumab, Pertuzumab, and Trastuzumab emtansine (T-DM1). For instance, the antigen binding site of the anti-Her2 antibody may be a scFv fragment derived from the anti-Her2 antibody and particularly it may be a form in which a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 109 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 111 are linked through a peptide linker or without it.

In one embodiment, the anti-c-Met/anti-Her2 bispecific antibody may be those including (a) an anti-c-Met antibody or an antigen-binding fragment thereof, and (b) an anti-Her2 antibody or an antigen-binding fragment thereof, which is linked to the C terminus or N terminus, for example, C terminus, of the anti-c-Met antibody or the antigen-binding fragment thereof.

In the anti-c-Met/anti-Her2 bispecific antibody, in order to fully perform the anti-c-Met antibody's activity to mediate intracellular migration and degradation of c-Met proteins, it may be advantageous that the anti-c-Met antibody has its own intact antibody structure. In addition, in case of the anti-Her2 antibody, its specific recognition and binding to Her2 is important, and, thus, just an antigen-binding fragment recognizing Her2 can be included in the bispecific antibody. Therefore, the anti-c-Met/anti-Her2 bispecific antibody may be those including a complete anti-c-Met antibody and an antigen-binding fragment of the anti-Her2 antibody linked to the C terminus of the anti-c-Met antibody.

In the anti-c-Met/anti-Her2 bispecific antibody, the anti-c-Met antibody or the antigen-binding fragment thereof, and the anti-Her2 antibody or the antigen-binding fragment thereof may be linked via a peptide linker or without it. Furthermore, a heavy chain portion and a light chain portion within the antigen-binding fragment, for example, a heavy chain variable region and a light chain variable region within the scFv fragment may be linked via a peptide linker or without it.

The peptide linker which links the anti-c-Met antibody or the antigen-binding fragment thereof, and the anti-Her2 antibody or the antigen-binding fragment thereof, and the peptide linker which links the heavy chain portion and the light chain portion within the antigen-binding fragment may be identical or different. The peptide linker may be those including any amino acids of 2 to 50, particularly 10 to 25 (e.g., 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24) amino acids, and any kinds of amino acids may be included without any restrictions. In particular, the peptide linker may include one or more residues selected from the group consisting of Gly, Asn and Ser, and also include neutral amino acids such as Thr and/or Ala. Amino acid sequences suitable for the peptide linker may be those known in the pertinent art. Meanwhile, a length of the peptide linker may be variously determined within such a limit that the functions of the fusion protein will not be affected. For instance, the peptide linker may be represented as (G₄S)_(n) (SEQ ID NO: 115) (n is a repeat number of G₄S (SEQ ID NO: 117), which is an integer of 1 to 10, particularly an integer of 2 to 5 (e.g., 3 or 4).

The “antigen-binding fragment” refers to fragments of a full immunoglobulin structure including a portion capable of binding to an antigen. For example, the antigen-binding fragment may be scFv, (scFv)₂, Fab, Fab′ or F(ab′)2, but is not limited thereto.

Of the antigen-binding fragments, Fab is a structure having variable regions of a light chain and a heavy chain, a constant region of the light chain, and the first constant region (C_(H1)) of the heavy chain, and it includes one antigen binding site.

Fab′ is different from Fab in that it includes a hinge region including one or more cysteine residues at the C-terminal of heavy chain C_(H1) domain. An F(ab′)₂ antibody is formed through disulfide bond of the cysteine residues at the hinge region of Fab′.

Fv is a minimal antibody piece including only a heavy chain variable region and light chain variable region, and a recombinant technique for producing the Fv fragment is well known in the pertinent art. Two-chain Fv may have a structure in which the heavy chain variable region is linked to the light chain variable region by a non-covalent bond, and single-chain Fv (scFv) may generally have a dimer structure as in the two-chain Fv in which the variable region of a heavy chain and the variable region of a light chain are covalently linked via a peptide linker or they are directly linked to each other at the C-terminal thereof. The peptide linker which links the heavy chain variable region and the light chain variable region may be those including any amino acids of 2 to 50, particularly 10 to 25 (e.g., 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24) amino acids, and any kinds of amino acids may be included without any restrictions.

The antigen-binding fragments may be obtained using proteases (for example, a whole antibody is digested with papain to obtain Fab fragments, and is digested with pepsin to obtain F(ab′)2 fragments), and may be prepared by a genetic recombinant technique.

In a particular embodiment, the anti-c-Met/anti-Her2 bispecific antibody comprises an anti-c-Met antibody, and scFv, (scFv)₂, Fab, Fab′ or F(ab′)2, for example, scFv of the anti-Her2 antibody linked to the C terminal of the anti-c-Met antibody. The scFv, (scFv)₂, Fab, Fab′ or F(ab′)2 of an anti-Her2 antibody may comprise a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 109 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 111.

In a particular embodiment, the anti-c-Met/anti-Her2 bispecific antibody comprises an anti-c-Met antibody, and scFv, (scFv)₂, Fab, Fab′ or F(ab′)2 of an anti-Her2 antibody comprising a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 109 and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 111, linked to the C terminus of the anti-c-Met antibody.

The anti c-Met antibody may recognize a specific region of c-Met, e.g., a specific region in the SEMA domain, as an epitope. It may be any antibody or antigen-binding fragment that acts on c-Met to induce c-Met intracellular internalization and degradation.

c-Met, a receptor for hepatocyte growth factor (HGF), may be divided into three portions: extracellular, transmembrane, and intracellular. The extracellular portion is composed of an α-subunit and a β-subunit which are linked to each other through a disulfide bond. The extracellular portion contains a SEMA domain responsible for binding HGF, a PSI domain (plexin-semaphorins-integrin homology domain) and an IPT domain (immunoglobulin-like fold shared by plexins and transcriptional factors domain). The SEMA domain of c-Met protein may comprise the amino acid sequence of SEQ ID NO: 79, and is an extracellular domain that functions to bind HGF. A specific region of the SEMA domain, that is, a region comprising the amino acid sequence of SEQ ID NO: 71, which corresponds to a range from amino acid residues 106 to 124 of the amino acid sequence of the SEMA domain (SEQ ID NO: 79) of c-Met protein, is a loop region between the second and the third propellers within the epitopes of the SEMA domain. The region acts as an epitope for the specific anti-c-Met antibody of the present invention.

The term “epitope” as used herein, refers to an antigenic determinant, a part of an antigen recognized by an antibody. In one embodiment, the epitope may be a region including 5 or more contiguous (consecutive or non-consecutive) amino acid residues within the SEMA domain (SEQ ID NO: 79) of c-Met protein, for instance, 5 to 19 (e.g., 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18) contiguous amino acid residues within the amino acid sequence of SEQ ID NO: 71. For example, the epitope may be a polypeptide including 5 to 19 contiguous amino acids selected from among partial combinations of the amino acid sequence of SEQ ID NO: 71, wherein the polypeptide essentially includes the amino sequence of SEQ ID NO: 73 (EEPSQ) serving as an essential element for the epitope. For example, the epitope may be a polypeptide comprising, consisting essentially of, or consisting of the amino acid sequence of SEQ ID NO: 71, SEQ ID NO: 72, or SEQ ID NO: 73.

The epitope comprising the amino acid sequence of SEQ ID NO: 72 corresponds to the outermost part of the loop between the second and third propellers within the SEMA domain of a c-Met protein. The epitope comprising the amino acid sequence of SEQ ID NO: 73 is a site to which the antibody or antigen-binding fragment according to one embodiment most specifically binds.

Thus, the anti-c-Met antibody may specifically bind to an epitope which includes 5 to 19 contiguous amino acids selected from among partial combinations of the amino acid sequence of SEQ ID NO: 71, including SEQ ID NO: 73 as an essential element. For example, the anti-c-Met antibody may specifically bind to an epitope including the amino acid sequence of SEQ ID NO: 71, SEQ ID NO: 72, or SEQ ID NO: 73.

In one embodiment, the anti-c-Met antibody may be an antibody or an antigen-binding fragment thereof, which includes:

(i) a heavy chain variable region including at least one heavy chain complementarity determining region (CDR) selected from the group consisting of (a) a CDR-H1 comprising the amino acid sequence of SEQ ID NO: 4; (b) a CDR-H2 comprising the amino acid sequence of SEQ ID NO: 5, the amino acid sequence of SEQ ID NO: 2, or an amino acid sequence comprising 8-19 consecutive amino acids including amino acid residues from the 3^(rd) to 10^(th) positions of SEQ ID NO: 2; and (c) a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 6, the amino acid sequence of SEQ ID NO: 85, or an amino acid sequence comprising 6-13 consecutive amino acids including amino acid residues from the 1^(st) to 6^(th) positions of the amino acid sequence of SEQ ID NO: 85; and

(ii) a light chain variable region including at least one light chain complementarity determining region (CDR) selected from the group consisting of (a) a CDR-L1 comprising the amino acid sequence of SEQ ID NO: 7, (b) a CDR-L2 comprising the amino acid sequence of SEQ ID NO: 8, and (c) a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 9, the amino acid sequence of SEQ ID NO: 86, or an amino acid sequence including 9-17 consecutive amino acids including amino acid residues from the 1^(st) to 9^(th) positions of the amino acid sequence of SEQ ID NO: 89.

Herein, the amino acid sequences of SEQ ID NOS: 4 to 9 are respectively represented by following Formulas I to VI, below: Xaa₁-Xaa₂-Tyr-Tyr-Met-Ser (SEQ ID NO: 4), wherein Xaa₁ is absent or Pro or Ser, and Xaa₂ is Glu or Asp,  Formula I: Arg-Asn-Xaa₃-Xaa₄-Asn-Gly-Xaa₅-Thr (SEQ ID NO: 5), wherein Xaa₃ is Asn or Lys, Xaa₄ is Ala or Val, and Xaa₅ is Asn or Thr,  Formula II: Asp-Asn-Trp-Leu-Xaa₆-Tyr (SEQ ID NO: 6), wherein Xaa₆ is Ser or Thr,  Formula III: Lys-Ser-Ser-Xaa₇-Ser-Leu-Leu-Ala-Xaa₈-Gly-Asn-Xaa₉-Xaa₁₀-Asn-Tyr-Leu-Ala (SEQ ID NO: 7), wherein Xaa₇ is His, Arg, Gln, or Lys, Xaa₈ is Ser or Trp, Xaa₉ is His or Gln, and Xaa₁₀ is Lys or Asn,  Formula IV: Trp-Xaa₁₁-Ser-Xaa₁₂-Arg-Val-Xaa₁₃ (SEQ ID NO: 8), wherein Xaa₁₁ is Ala or Gly, Xaa₁₂ is Thr or Lys, and Xaa₁₃ is Ser or Pro, and  Formula V: Xaa₁₄-Gln-Ser-Tyr-Ser-Xaa₁₅-Pro-Xaa₁₆-Thr (SEQ ID NO: 9), wherein Xaa₁₄ is Gly, Ala, or Gln, Xaa₁₅ is Arg, His, Ser, Ala, Gly, or Lys, and Xaa₁₆ is Leu, Tyr, Phe, or Met.  Formula VI:

In one embodiment, the CDR-H1 may comprise an amino acid sequence selected from the group consisting of SEQ ID NOS: 1, 22, 23, and 24. The CDR-H2 may comprise an amino acid sequence selected from the group consisting of SEQ ID NOS: 2, 25, and 26. The CDR-H3 may comprise an amino acid sequence selected from the group consisting of SEQ ID NOS: 3, 27, 28, and 85.

The CDR-L1 may comprise an amino acid sequence selected from the group consisting of SEQ ID NOS: 10, 29, 30, 31, 32, 33, and 106. The CDR-L2 may comprise an amino acid sequence selected from the group consisting of SEQ ID NOS: 11, 34, 35, and 36. The CDR-L3 may comprise an amino acid sequence selected from the group consisting of SEQ ID NOS: 12, 13, 14, 15, 16, 37, 86, and 89.

In another embodiment, the antibody or the antigen-binding fragment may comprise a heavy variable region including a polypeptide (CDR-H1) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 1, 22, 23, and 24, a polypeptide (CDR-H2) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 2, 25, and 26, and a polypeptide (CDR-H3) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 3, 27, 28, and 85; and a light variable region comprising a polypeptide (CDR-L1) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 10, 29, 30, 31, 32, 33 and 106, a polypeptide (CDR-L2) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 11, 34, 35, and 36, and a polypeptide (CDR-L3) comprising an amino acid sequence selected from the group consisting of SEQ ID NOS 12, 13, 14, 15, 16, 37, 86, and 89.

Animal-derived antibodies produced by immunizing non-immune animals with a desired antigen generally invoke immunogenicity when injected into humans for the purpose of medical treatment, and thus chimeric antibodies have been developed to inhibit such immunogenicity. Chimeric antibodies are prepared by replacing constant regions of animal-derived antibodies that cause an anti-isotype response with constant regions of human antibodies by genetic engineering. Chimeric antibodies are considerably improved in an anti-isotype response compared to animal-derived antibodies, but animal-derived amino acids still have variable regions, so that chimeric antibodies have side effects with respect to a potential anti-idiotype response. Humanized antibodies have been developed to reduce such side effects. Humanized antibodies are produced by grafting complementarity determining regions (CDR) which serve an important role in antigen binding in variable regions of chimeric antibodies into a human antibody framework.

The most important thing in CDR grafting to produce humanized antibodies is choosing the optimized human antibodies for accepting CDRs of animal-derived antibodies. Antibody databases, analysis of a crystal structure, and technology for molecule modeling are used. However, even when the CDRs of animal-derived antibodies are grafted to the most optimized human antibody framework, amino acids positioned in a framework of the animal-derived CDRs affecting antigen binding are present. Therefore, in many cases, antigen binding affinity is not maintained, and thus application of additional antibody engineering technology for recovering the antigen binding affinity is necessary.

The anti c-Met antibodies may be mouse-derived antibodies, mouse-human chimeric antibodies, humanized antibodies, or human antibodies. The antibodies or antigen-binding fragments thereof may be isolated from (not originally present in) a living body or non-naturally occurring. The antibodies or antigen-binding fragments thereof may be recombinant or synthetic.

An intact antibody includes two full-length light chains and two full-length heavy chains, in which each light chain is linked to a heavy chain by disulfide bonds. The antibody includes a heavy chain constant region and a light chain constant region. The heavy chain constant region is of a gamma (γ), mu (μ), alpha (α), delta (δ), or epsilon (ε) type, which may be further categorized as gamma 1 (γ1), gamma 2(γ2), gamma 3(γ3), gamma 4(γ4), alpha 1(α1), or alpha 2(α2). The light chain constant region is of either a kappa (κ) or lambda (λ) type.

As used herein, the term “heavy chain” refers to full-length heavy chain, and fragments thereof, including a variable region V_(H) that includes amino acid sequences sufficient to provide specificity to antigens, and three constant regions, C_(H1), C_(H2), and C_(H3), and a hinge. The term “light chain” refers to a full-length light chain and fragments thereof, including a variable region V_(L) that includes amino acid sequences sufficient to provide specificity to antigens, and a constant region C_(L).

The term “complementarity determining region (CDR)” refers to an amino acid sequence found in a hyper variable region of a heavy chain or a light chain of immunoglobulin. The heavy and light chains may respectively include three CDRs (CDRH1, CDRH2, and CDRH3; and CDRL1, CDRL2, and CDRL3). The CDRs may provide contact residues that play an important role in the binding of antibodies to antigens or epitopes. The terms “specifically binding” and “specifically recognized” are well known to one of ordinary skill in the art, and indicate that an antibody and an antigen specifically interact with each other to lead to an immunological activity.

The term “antigen-binding fragment” used herein refers to fragments of an intact immunoglobulin including portions of a polypeptide that comprises antigen-binding regions having the ability to specifically bind to the antigen. In one embodiment, the antibody may be an antigen-binding fragment selected from the group consisting of scFv, (scFv)₂, Fab, Fab′, and F(ab′)2.

Among the antigen-binding fragments, Fab that includes light chain and heavy chain variable regions, a light chain constant region, and a first heavy chain constant region C_(H1), includes one antigen-binding site.

The Fab′ fragment is different from the Fab fragment, in that Fab′ includes a hinge region with at least one cysteine residue at the C-terminal of C_(H1).

The F(ab′)2 antibody is formed through disulfide bridging of the cysteine residues in the hinge region of the Fab′ fragment. Fv is the smallest antibody fragment with only a heavy chain variable region and a light chain variable region. Recombination techniques of generating the Fv fragment are widely known in the art.

Two-chain Fv includes a heavy chain variable region and a light chain region which are linked by a non-covalent bond. Single-chain Fv generally includes a heavy chain variable region and a light chain variable region which are linked by a covalent bond via a peptide linker or linked at the C-terminals to have a dimer structure like the two-chain Fv.

The antigen-binding fragments may be attainable using protease (for example, the Fab fragment may be obtained by restricted cleavage of a whole antibody with papain, and the F(ab′)2 fragment may be obtained by cleavage with pepsin), or may be prepared by using a genetic recombination technique.

The term “hinge region,” as used herein, refers to a region between CH1 and CH2 domains within the heavy chain of an antibody which functions to provide flexibility for the antigen-binding site.

When an animal antibody undergoes a chimerization process, the IgG1 hinge of animal origin may be replaced with a human IgG1 hinge or IgG2 hinge while the disulfide bridges between two heavy chains are reduced from three to two in number. In addition, an animal-derived IgG1 hinge is shorter than a human IgG1 hinge. Accordingly, the rigidity of the hinge is changed. Thus, a modification of the hinge region may bring about an improvement in the antigen binding efficiency of the humanized antibody. The modification of the hinge region through amino acid deletion, addition, or substitution is well-known to those skilled in the art.

In one embodiment, the anti-c-Met antibody or an antigen-binding fragment thereof may be modified by the deletion, insertion, addition, or substitution of at least one (e.g., two, three, four, five, six, seven, eight, nine, or ten) amino acid residue of the amino acid sequence of the hinge region so that it exhibits enhanced antigen-binding efficiency. For example, the antibody may include a hinge region including the amino acid sequence of SEQ ID NO: 100 (U7-HC6), 101 (U6-HC7), 102 (U3-HC9), 103 (U6-HC8), or 104 (U8-HC5), or a hinge region including the amino acid sequence of SEQ ID NO: 105 (non-modified human hinge). Preferably, the hinge region includes the amino acid sequence of SEQ ID NO: 100 or 101.

In one embodiment of the anti-c-Met antibody or antigen-binding fragment, the variable domain of the heavy chain comprises the amino acid sequence of SEQ ID NO: 17, 74, 87, 90, 91, 92, 93, or 94 and the variable domain of the light chain comprises the amino acid sequence of SEQ ID NO: 18, 19, 20, 21, 75, 88, 95, 96, 97, 98, 99, or 107.

In one embodiment, the anti-c-Met antibody may be a monoclonal antibody.

The monoclonal antibody may be produced by the hybridoma cell line deposited with the Korean Cell Line Research Foundation, an international depository authority located at Yungun-Dong, Jongno-Gu, Seoul, Korea, on Oct. 9, 2009, under Accession No. KCLRF-BP-00220, which binds specifically to the extracellular region of c-Met protein (refer to Korean Patent Publication No. 2011-0047698, the entire disclosure of which is incorporated herein by reference). The anti-c-Met antibody may include all the antibodies defined in Korean Patent Publication No. 2011-0047698.

In the anti-c-Met antibody, the portion of the light chain and the heavy chain portion excluding the CDRs, the light chain variable region, and the heavy chain variable region refers to the light chain constant region and the heavy chain constant region. The heavy chain constant region, the light chain constant region, and/or the region other than the CDR region, the heavy chain variable region, or the light chain variable region may be originated from any subtype of immunoglobulin (e.g., IgA, IgD, IgE, IgG (IgG1, IgG2, IgG3, IgG4), IgM, etc.).

By way of further example, the anti-c-Met antibody or the antibody fragment may include:

(a) a heavy chain comprising an amino acid sequence selected from the group consisting of the amino acid sequence of SEQ ID NO: 62 (wherein the amino acid sequence from amino acid residues from the 1^(st) to 17^(th) positions is a signal peptide), the amino acid sequence from the 18^(th) to 462^(nd) positions of SEQ ID NO: 62, the amino acid sequence of SEQ ID NO: 64 (wherein the amino acid sequence from the 1^(st) to 17^(th) positions is a signal peptide), the amino acid sequence from the 18^(th) to 461^(st) positions of SEQ ID NO: 64, the amino acid sequence of SEQ ID NO: 66 (wherein the amino acid sequence from the 1^(st) to 17^(th) positions is a signal peptide), and the amino acid sequence from the 18^(th) to 460^(th) positions of SEQ ID NO: 66; and

(b) a light chain comprising an amino acid sequence selected from the group consisting of the amino acid sequence of SEQ ID NO: 68 (wherein the amino acid sequence from the 1^(st) to 20^(th) positions is a signal peptide), the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 68, the amino acid sequence of SEQ ID NO: 70 (wherein the amino acid sequence from the 1^(st) to 20^(th) positions is a signal peptide), the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 70, and the amino acid sequence of SEQ ID NO: 108.

For example, the anti-c-Met antibody may be selected from the group consisting of:

(i) an antibody comprising (a) a heavy chain comprising the amino acid sequence of SEQ ID NO: 62 or the amino acid sequence from the 18^(th) to 462^(nd) positions of SEQ ID NO: 62 and (b) a light chain comprising the amino acid sequence of SEQ ID NO: 68 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 68;

(ii) an antibody comprising (a) a heavy chain comprising the amino acid sequence of SEQ ID NO: 64 or the amino acid sequence from the 18^(th) to 461^(st) positions of SEQ ID NO: 64 and (b) a light chain including the amino acid sequence of SEQ ID NO: 68 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 68;

(iii) an antibody comprising (a) a heavy chain comprising the amino acid sequence of SEQ ID NO: 66 or the amino acid sequence from the 18^(th) to 460^(th) positions of SEQ ID NO: 66 and (b) a light chain comprising the amino acid sequence of SEQ ID NO: 68 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 68;

(iv) an antibody comprising (a) a heavy chain comprising the amino acid sequence of SEQ ID NO: 62 or the amino acid sequence from the 18^(th) to 462^(nd) positions of SEQ ID NO: 62 and (b) a light chain including the amino acid sequence of SEQ ID NO: 70 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 70;

(v) an antibody comprising a heavy chain comprising (a) the amino acid sequence of SEQ ID NO: 64 or the amino acid sequence from the 18^(th) to 461^(st) positions of SEQ ID NO: 64 and (b) a light chain comprising the amino acid sequence of SEQ ID NO: 70 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 70;

(v) an antibody comprising (a) a heavy chain comprising the amino acid sequence of SEQ ID NO: 66 or the amino acid sequence from the 18^(th) to 460^(th) positions of SEQ ID NO: 66 and (b) a light chain comprising the amino acid sequence of SEQ ID NO: 70 or the amino acid sequence from the 21^(st) to 240^(th) positions of SEQ ID NO: 70;

(vi) an antibody comprising (a) a heavy chain comprising the amino acid sequence of SEQ ID NO: 62 or the amino acid sequence from the 18^(th) to 462^(nd) positions of SEQ ID NO: 62 and (b) a light chain comprising the amino acid sequence of SEQ ID NO: 108;

(vii) an antibody comprising (a) a heavy chain comprising the amino acid sequence of SEQ ID NO: 64 or the amino acid sequence from the 18^(th) to 461^(st) positions of SEQ ID NO: 64 and (b) a light chain comprising the amino acid sequence of SEQ ID NO: 108; and

(viii) an antibody comprising (a) a heavy chain comprising the amino acid sequence of SEQ ID NO: 66 or the amino acid sequence from the 18^(th) to 460^(th) positions of SEQ ID NO: 66 and (b) a light chain comprising the amino acid sequence of SEQ ID NO: 108.

The polypeptide comprising the amino acid sequence of SEQ ID NO: 70 is a light chain including human kappa (κ) constant region, and the polypeptide comprising the amino acid sequence of SEQ ID NO: 68 is a polypeptide obtained by replacing histidine at position 62 (corresponding to position 36 of SEQ ID NO: 68 according to kabat numbering) of the polypeptide comprising the amino acid sequence of SEQ ID NO: 70 with tyrosine. The production yield of the antibodies may be increased by the replacement. The polypeptide comprising the amino acid sequence of SEQ ID NO: 108 is a polypeptide obtained by replacing serine at position 32 (position 27e according to kabat numbering in the amino acid sequence from amino acid residues 21 to 240 of SEQ ID NO: 68; positioned within CDR-L1) of SEQ ID NO: 108 with tryptophan. By such replacement, antibodies and antibody fragments including such sequences exhibit increased activities, such as c-Met biding affinity, c-Met degradation activity, Akt phosphorylation inhibition, and the like.

In another embodiment, the anti c-Met antibody may include a light chain complementarity determining region comprising the amino acid sequence of SEQ ID NO: 106, a light chain variable region comprising the amino acid sequence of SEQ ID NO: 107, or a light chain comprising the amino acid sequence of SEQ ID NO: 108.

The anti-c-Met/anti-Her2 bispecific antibody can not only inhibit the activity of c-Met and Her2 by the internalization and degradation activity of anti-c-Met antibody but also fundamentally block them by reducing the total amounts of c-Met and Her2 by the degradation thereof. Accordingly, the anti-c-Met/anti-Her2 bispecific antibody can obtain efficient effects even when applied to patients who have developed resistance against pre-existing anti-Her2 antibodies.

An embodiment provides a pharmaceutical composition including an anti-c-Met/anti-Her2 bispecific antibody (e.g., in combination with a pharmaceutically acceptable carrier).

Another embodiment provides a method for preventing and/or treating cancer including administering a pharmaceutically effective amount of the anti-c-Met/anti-Her2 bispecific antibody (alone or in combination with a pharmaceutically acceptable carrier) to a patient in need of the prevention and/or treatment of cancer. The method may further include the step of identifying the patient in need of the prevention and/or treatment of cancer prior to the step of administering. Another embodiment provides a use of the anti-c-Met/anti-Her2 bispecific antibody for the prevention and/or treatment of cancer.

The cancer to be prevented and/or treated by the anti-c-Met/anti-Her2 bispecific antibody may be associated with over-expression and/or abnormal activation of c-Met and/or Her2. The cancer may include solid cancers and blood cancers. The cancer may be, but not limited to, one or more selected from the group consisting of squamous cell carcinoma, small-cell lung cancer, non-small-cell lung cancer, adenocarcinoma of the lung, squamous cell carcinoma of the lung, peritoneal carcinoma, skin cancer, melanoma in the skin or eyeball, rectal cancer, cancer near the anus, esophagus cancer, small intestinal tumor, endocrine gland cancer, parathyroid cancer, adrenal cancer, soft-tissue sarcoma, urethral cancer, chronic or acute leukemia, lymphocytic lymphoma, hepatoma, gastric cancer, gastrointestinal cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatocellular adenoma, breast cancer, colon cancer, large intestine cancer, endometrial carcinoma or uterine carcinoma, salivary gland tumor, kidney cancer, prostate cancer, vulvar cancer, thyroid cancer, head or neck cancer, and brain cancer. The cancer may include metastatic cancers as well as primary cancers. Especially, the cancer may be a cancer having resistance against pre-existing anticancer drugs, for example, antagonists against Her2.

The prevention and/or treatment of cancer may include cancer cell death, inhibition of cancer cell proliferation, improvement of symptoms associated with cancer, inhibition of metastasis of cancer, etc.

The pharmaceutical composition may be provided along with a pharmaceutically acceptable carrier, diluent, and/or excipient, in addition to a pharmaceutically effective amount of the anti-c-Met/anti-Her2 bispecific antibody.

The pharmaceutically acceptable carrier to be included in the composition may be those commonly used for the formulation of antibodies, which may be one or more selected from the group consisting of lactose, dextrose, sucrose, sorbitol, mannitol, starch, gum acacia, calcium phosphate, alginates, gelatin, calcium silicate, micro-crystalline cellulose, polyvinylpyrrolidone, cellulose, water, syrup, methyl cellulose, methylhydroxy benzoate, propylhydroxy benzoate, talc, magnesium stearate, and mineral oil, but are not limited thereto. The pharmaceutical composition may further include one or more selected from the group consisting of a lubricant, a wetting agent, a sweetener, a flavor enhancer, an emulsifying agent, a suspension agent, and preservative.

The pharmaceutical composition may be administered orally or parenterally. The parenteral administration may include intravenous injection, subcutaneous injection, muscular injection, intraperitoneal injection, endothelial administration, local administration, intranasal administration, intrapulmonary administration, and rectal administration. Since oral administration leads to digestion of proteins or peptides, an active ingredient in the compositions for oral administration must be coated or formulated to prevent digestion in stomach. In addition, the compositions may be administered using an optional device that enables an active substance to be delivered to target cells.

A suitable dosage of the pharmaceutical composition may be prescribed in a variety of ways, depending on factors such as formulation methods, administration methods, age of patients, body weight, gender, pathologic conditions, diets, administration time, administration route, excretion speed, and reaction sensitivity. A desirable dosage of the pharmaceutical composition may be in the range of about 0.001 to 100 mg/kg (body weight) per day for an adult. The term “the pharmaceutically effective amount” as used in this specification refers to an amount at which each active ingredient can exert pharmaceutically significant effects in preventing or treating cancer.

The pharmaceutical composition may be formulated with a pharmaceutically acceptable carrier and/or excipient into a unit or a multiple dosage form by a method easily carried out by a skilled person in the pertinent art. The dosage form may be a solution in oil or an aqueous medium, a suspension, syrup, an emulsifying solution, an extract, powder, granules, a tablet, or a capsule, and may further include a dispersing or a stabilizing agent.

In addition, the pharmaceutical composition may be administered as an individual drug, or together with other drugs, and may be administered sequentially or simultaneously with pre-existing drugs.

Since the pharmaceutical composition includes an antibody or an antigen-binding fragment thereof, it may be formulated as an immunoliposome. The liposome containing the antibody may be prepared using a well-known method in the pertinent art. The immunoliposome is a lipid composition including phosphatidylcholine, cholesterol, and polyethyleneglycol-derivatized phosphatidylethanolamine, and may be prepared by a reverse phase evaporation method. For example, Fab′ fragments of an antibody may be conjugated to the liposome through a disulfide exchange reaction. A chemical drug such as doxorubicin may be additionally included in the liposome.

The subjects to which the pharmaceutical composition is administered or patients to which the preventing and/treating method is administered may be mammals, for example, primates such as humans and monkeys, or rodents such as rats and mice, but are not limited thereto, and they may be cancer patients having resistance against pre-existing anticancer drugs, for example, antagonists against the target cell membrane proteins.

Herceptin, which is a typical target drug recognizing only Her2 which is a typical target expressed abundantly in cancer cells, induces the over-expression and activation of cMet and thus causes cancer cells to acquire resistance against drugs, whereby the therapeutic effects could be reduced. In this regard, the inventors have verified that a bispecific antibody recognizing cMet and Her2 at the same time suppresses the over-expression of cMet which is a cause of resistance against drugs and thus blocks its signal transduction in advance to prevent the development of resistance and shows excellent cancer cell suppression effects even in cancer cells having resistance. The bispecific cMet/Her2 antibody which is the subject matter of the present invention exceeds the efficiency of the pre-existing single target drugs and at the same time, it is expected to exhibit effects even in cancers where the pre-existing drugs exerted no effects.

Hereafter, the present invention will be described in detail by examples.

The following examples are intended merely to illustrate the invention and are not construed to restrict the invention.

EXAMPLES Reference Example 1: Construction of Anti-c-Met Antibody

1.1. Production of “AbF46”, a Mouse Antibody to c-Met

1.1.1. Immunization of Mouse

To obtain immunized mice necessary for the development of a hybridoma cell line, each of five BALB/c mice (Japan SLC, Inc.), 4 to 6 weeks old, was intraperitoneally injected with a mixture of 100 μg of human c-Met/Fc fusion protein (R&D Systems) and one volume of complete Freund's adjuvant. Two weeks after the injection, a second intraperitoneal injection was conducted on the same mice with a mixture of 50 μg of human c-Met/Fc protein and one volume of incomplete Freund's adjuvant. One week after the second immunization, the immune response was finally boosted. Three days later, blood was taken from the tails of the mice and the sera were 1/1000 diluted in PBS and used to examine a titer of antibody to c-Met by ELISA. Mice found to have a sufficient antibody titer were selected for use in the cell fusion process.

1.1.2. Cell Fusion and Production of Hybridoma

Three days before cell fusion, BALB/c mice (Japan SLC, Inc.) were immunized with an intraperitoneal injection of a mixture of 50 μg of human c-Met/Fc fusion protein and one volume of PBS. The immunized mice were anesthetized before excising the spleen from the left half of the body. The spleen was meshed to separate splenocytes which were then suspended in a culture medium (DMEM, GIBCO, Invitrogen). The cell suspension was centrifuged to recover the cell layer. The splenocytes thus obtained (1×10⁸ cells) were mixed with myeloma cells (Sp2/0) (1×10⁸ cells), followed by spinning to give a cell pellet. The cell pellet was slowly suspended, treated with 45% polyethylene glycol (PEG) (1 mL) in DMEM for 1 min at 37° C., and supplemented with 1 mL of DMEM. To the cells was added 10 mL of DMEM over 10 min, after which incubation was conducted in a water bath at 37° C. for 5 min. Then the cell volume was adjusted to 50 mL before centrifugation. The cell pellet thus formed was resuspended at a density of 1-2×10⁵ cells/mL in a selection medium (HAT medium) and 0.1 mL of the cell suspension was allocated to each well of 96-well plates which were then incubated at 37° C. in a CO₂ incubator to establish a hybridoma cell population.

1.1.3. Selection of Hybridoma Cells Producing Monoclonal Antibodies to c-Met Protein

From the hybridoma cell population established in Reference Example 1.1.2, hybridoma cells which showed a specific response to c-Met protein were screened by ELISA using human c-Met/Fc fusion protein and human Fc protein as antigens.

Human c-Met/Fc fusion protein was seeded in an amount of 50 μL (2 μg/mL)/well to microtiter plates and allowed to adhere to the surface of each well. The antibody that remained unbound was removed by washing. For use in selecting the antibodies that do not bind c-Met but recognize Fc, human Fc protein was attached to the plate surface in the same manner.

The hybridoma cell culture obtained in Reference Example 1.1.2 was added in an amount of 50 μL to each well of the plates and incubated for 1 hour. The cells remaining unreacted were washed out with a sufficient amount of Tris-buffered saline and TWEEN 20 (polysorbate 20) (TBST). Goat anti-mouse IgG-horseradish peroxidase (HRP) was added to the plates and incubated for 1 hour at room temperature. The plates were washed with a sufficient amount of TBST, followed by reacting the peroxidase with a substrate (OPD). Absorbance at 450 nm was measured on an ELISA reader.

Hybridoma cell lines which secrete antibodies that specifically and strongly bind to human c-Met but not human Fc were selected repeatedly. From the hybridoma cell lines obtained by repeated selection, a single clone producing a monoclonal antibody was finally separated by limiting dilution. The single clone of the hybridoma cell line producing the monoclonal antibody was deposited with the Korean Cell Line Research Foundation, an international depository authority located at Yungun-Dong, Jongno-Gu, Seoul, Korea, on Oct. 9, 2009, with Accession No. KCLRF-BP-00220 according to the Budapest Treaty (refer to Korean Patent Laid-Open Publication No. 2011-0047698).

1.1.4. Production and Purification of Monoclonal Antibody

The hybridoma cell line obtained in Reference Example 1.1.3 was cultured in a serum-free medium, and the monoclonal antibody (AbF46) was produced and purified from the cell culture.

First, the hybridoma cells cultured in 50 mL of a medium (DMEM) supplemented with 10% (v/v) fetal bovine serum (FBS) were centrifuged and the cell pellet was washed twice or more with 20 mL of PBS to remove the FBS therefrom. Then, the cells were resuspended in 50 mL of DMEM and incubated for 3 days at 37° C. in a CO₂ incubator.

After the cells were removed by centrifugation, the supernatant was stored at 4° C. before use or immediately used for the separation and purification of the antibody. An AKTA fast protein liquid chromatography system (GE Healthcare) equipped with an affinity column (Protein G agarose column; Pharmacia, USA) was used to purify the antibody from 50 to 300 mL of the supernatant, followed by concentration with a filter (Amicon). The antibody in phosphate buffered saline (PBS) was stored before use in the following examples.

1.2. Construction of chAbF46, a Chimeric Antibody to c-Met

A mouse antibody is apt to elicit immunogenicity in humans. To solve this problem, chAbF46, a chimeric antibody, was constructed from the mouse antibody AbF46 produced in Experimental Example 1.1.4 by replacing the constant region, but not the variable region responsible for antibody specificity, with an amino sequence of the human IgG1 antibody.

In this regard, a gene was designed to include the nucleotide sequence of “EcoRI-signal sequence-VH-NheI-CH-TGA-XhoI” (SEQ ID NO: 38) for a heavy chain and the nucleotide sequence of “EcoRI-signal sequence-VL-BsiWI-CL-TGA-XhoI” (SEQ ID NO: 39) for a light chain and synthesized. Then, a DNA fragment having the heavy chain nucleotide sequence (SEQ ID NO: 38) and a DNA fragment having the light chain nucleotide sequence (SEQ ID NO: 39) were digested with EcoRI (NEB, R0101S) and XhoI (NEB, R0146S) before cloning into a vector from the pOptiVEC™-TOPO TA Cloning Kit enclosed in an OptiCHO™ Antibody Express Kit (Cat no. 12762-019, Invitrogen), and a vector from the pcDNA™3.3-TOPO TA Cloning Kit (Cat no. 8300-01), respectively.

Each of the constructed vectors was amplified using Qiagen Maxiprep kit (Cat no. 12662), and a transient expression was performed using Freestyle™ MAX 293 Expression System (Invitrogen). 293 F cells were used for the expression and cultured in FreeStyle™ 293 Expression Medium in a suspension culture manner. At one day before the transient expression, the cells were provided in the concentration of 5×10⁵ cells/mL, and after 24 hours, when the cell number reached to 1×10⁶ cells/mL, the transient expression was performed. A transfection was performed by a liposomal reagent method using Freestyle™ MAX reagent (Invitrogen), wherein in a 15 mL tube, the DNA was provided in the mixture ratio of 1:1 (heavy chain DNA:light chain DNA) and mixed with 2 ml of OptiPro™ SFM (Invitrogen) (A). In another 15 ml tube, 100 μL of Freestyle™ MAX reagent and 2 mL of OptiPro™ SFM were mixed (B). This was followed by mixing (A) and (B) and incubating for 15 minutes. The obtained mixture was slowly mixed with the cells provided one day before the transient expression. After completing the transfection, the cells were incubated in 130 rpm incubator for 5 days under the conditions of 37° C., 80% humidity, and 8% CO₂.

Afterwards, the cells were incubated in DMEM supplemented with 10% (v/v) FBS for 5 hours at 37° C. under a 5% CO₂ condition and then in FBS-free DMEM for 48 hours at 37° C. under a 5% CO₂ condition.

After centrifugation, the supernatant was applied to AKTA prime fast protein liquid chromatography (GE Healthcare) to purify the antibody. In this regard, 100 mL of the supernatant was loaded at a flow rate of 5 mL/min to AKTA Prime fast protein liquid chromatography equipped with a Protein A column (GE Healthcare, 17-0405-03), followed by elution with an IgG elution buffer (Thermo Scientific, 21004). The buffer was exchanged with PBS to purify a chimeric antibody AbF46 (hereinafter referred to as “chAbF46”).

1.3. Construction of Humanized Antibody huAbF46 from Chimeric Antibody chAbF46

1.3.1. Heavy Chain Humanization

To design two domains H1-heavy and H3-heavy, human germline genes which share the highest identity/homology with the VH gene of the mouse antibody AbF46 purified in Reference Example 1.2 were analyzed. An Ig BLAST (IgBLAST online database tool, maintained by National Center for Biotechnology Information (NCBI), Bethesda, Md.) result revealed that VH3-71 has an identity/identity/homology of 83% at the amino acid level. CDR-H1, CDR-H2, and CDR-H3 of the mouse antibody AbF46 were defined according to Kabat numbering. A design was made to introduce the CDRs of the mouse antibody AbF46 into the framework of VH3-71. Hereupon, back mutations to the amino acid sequence of the mouse AbF46 were conducted at positions 30 (S→T), 48 (V→L), 73 (D→N), and 78 (T→L). Then, H1 was further mutated at positions 83 (R→K) and 84 (A→T) to finally establish H1-heavy (SEQ ID NO: 40) and H3-heavy (SEQ ID NO: 41).

For use in designing H4-heavy, human antibody frameworks were analyzed by a BLAST search. The result revealed that the VH3 subtype, known to be most stable, is very similar in framework and sequence to the mouse antibody AbF46. CDR-H1, CDR-H2, and CDR-H3 of the mouse antibody AbF46 were defined according to Kabat numbering and introduced into the VH3 subtype to construct H4-heavy (SEQ ID NO: 42).

1.3.2. Light Chain Humanization

To design two domains H1-light (SEQ ID NO: 43) and H2-light (SEQ ID NO: 44), human germline genes which share the highest identity/homology with the VH gene of the mouse antibody AbF46 were analyzed. An Ig BLAST search result revealed that VK4-1 has an identity/homology of 75% at the amino acid level. CDR-L1, CDR-L2, and CDR-L3 of the mouse antibody AbF46 were defined according to Kabat numbering. A design was made to introduce the CDRs of the mouse antibody AbF46 into the framework of VK4-1. Hereupon, back mutations to the amino acid sequence of the mouse AbF46 were conducted at positions 36 (Y→H), 46 (L→M), and 49 (Y→I). Only one back mutation was conducted at position 49 (Y→I) on H2-light.

To design H3-light (SEQ ID NO: 45), human germline genes which share the highest identity/homology with the VL gene of the mouse antibody AbF46 were analyzed by a search for BLAST. As a result, VK2-40 was selected. VL and VK2-40 of the mouse antibody AbF46 were found to have an identity/homology of 61% at an amino acid level. CDR-L1, CDR-L2, and CDR-L3 of the mouse antibody were defined according to Kabat numbering and introduced into the framework of VK4-1. Back mutations were conducted at positions 36 (Y→H), 46 (L→M), and 49 (Y→I) on H3-light.

For use in designing H4-light (SEQ ID NO: 46), human antibody frameworks were analyzed. A Blast search revealed that the Vk1 subtype, known to be the most stable, is very similar in framework and sequence to the mouse antibody AbF46. CDR-L1, CDR-L2, and CDR-L3 of the mouse antibody AbF46 were defined according to Kabat numbering and introduced into the Vk1 subtype. Hereupon, back mutations were conducted at positions 36 (Y→H), 46 (L→M), and 49 (Y→I) on H4-light.

Thereafter, DNA fragments having the heavy chain nucleotide sequences (H1-heavy: SEQ ID NO: 47, H3-heavy: SEQ ID NO: 48, H4-heavy: SEQ ID NO: 49) and DNA fragments having the light chain nucleotide sequences (H1-light: SEQ ID NO: 50, H2-light: SEQ ID NO: 51, H3-light: SEQ ID NO: 52, H4-light: SEQ ID NO: 53) were digested with EcoRI (NEB, R0101S) and XhoI (NEB, R0146S) before cloning into a vector from the pOptiVEC™-TOPO TA Cloning Kit enclosed in an OptiCHO™ Antibody Express Kit (Cat no. 12762-019, Invitrogen) and a vector from the pcDNA™3.3-TOPO TA Cloning Kit (Cat no. 8300-01), respectively, so as to construct recombinant vectors for expressing a humanized antibody.

Each of the constructed vectors was amplified using Qiagen Maxiprep kit (Cat no. 12662), and a transient expression was performed using Freestyle™ MAX 293 Expression System (Invitrogen). 293 F cells were used for the expression and cultured in FreeStyle™ 293 Expression Medium in a suspension culture manner. At one day before the transient expression, the cells were provided in the concentration of 5×10⁵ cells/mL, and after 24 hours, when the cell number reached to 1×10⁶ cells/mL, the transient expression was performed. A transfection was performed by a liposomal reagent method using Freestyle™ MAX reagent (Invitrogen), wherein in a 15 mL tube, the DNA was provided in the mixture ratio of 1:1 (heavy chain DNA:light chain DNA) and mixed with 2 mL of OptiPro™ SFM (Invitrogen) (A). In another 15 mL tube, 100 μL of Freestyle™ MAX reagent and 2 mL of OptiPro™ SFM were mixed (B). This was followed by mixing (A) and (B) and incubating for 15 minutes. The obtained mixture was slowly mixed with the cells provided one day before the transient expression. After completing the transfection, the cells were incubated in 130 rpm incubator for 5 days under the conditions of 37° C., 80% humidity, and 8% CO₂.

After centrifugation, the supernatant was applied to AKTA prime fast protein liquid chromatography (GE Healthcare) to purify the antibody. In this regard, 100 mL of the supernatant was loaded at a flow rate of 5 mL/min to AKTA Prime fast protein liquid chromatography equipped with a Protein A column (GE Healthcare, 17-0405-03), followed by elution with an IgG elution buffer (Thermo Scientific, 21004). The buffer was exchanged with PBS to purify a humanized antibody AbF46 (hereinafter referred to as “huAbF46”). The humanized antibody huAbF46 used in the following examples included a combination of H4-heavy (SEQ ID NO: 42) and H4-light (SEQ ID NO: 46).

1.4. Construction of scFV Library of huAbF46 Antibody

For use in constructing an scFv of the huAbF46 antibody from the heavy and light chain variable regions of the huAbF46 antibody, a gene was designed to have the structure of “VH-linker-VL” for each of the heavy and the light chain variable region, with the linker including the amino acid sequence “GLGGLGGGGSGGGGSGGSSGVGS” (SEQ ID NO: 54). A polynucleotide sequence (SEQ ID NO: 55) encoding the designed scFv of huAbF46 was synthesized in BIONEER and an expression vector for the polynucleotide had the nucleotide sequence of SEQ ID NO: 56.

After expression, the product was found to exhibit specificity to c-Met.

1.5. Construction of Library Genes for Affinity Maturation

1.5.1. Selection of Target CDRs and Synthesis of Primers

The affinity maturation of huAbF46 was achieved. First, six complementary determining regions (CDRs) were defined according to Kabat numbering. The CDRs are given in Table 1, below.

TABLE 1  CDR Amino Acid Sequence CDR-H1 DYYMS (SEQ ID NO: 1) CDR-H2 FIRNKANGYTTEYSASVKG (SEQ ID NO: 2) CDR-H3 DNWFAY (SEQ ID NO: 3) CDR-L1 KSSQSLLASGNQNNYLA (SEQ ID NO: 10) CDR-L2 WASTRVS (SEQ ID NO: 11) CDR-L3 QQSYSAPLT (SEQ ID NO: 12)

For use in the introduction of random sequences into the CDRs of the antibody, primers were designed as follows. Conventionally, N codons were utilized to introduce bases at the same ratio (25% A, 25% G, 25% C, 25% T) into desired sites of mutation. In this experiment, the introduction of random bases into the CDRs of huAbF46 was conducted in such a manner that, of the three nucleotides per codon in the wild-type polynucleotide encoding each CDR, the first and second nucleotides conserved over 85% of the entire sequence while the other three nucleotides were introduced at the same percentage (each 5%) and that the same possibility was imparted to the third nucleotide (33% G, 33% C, 33% T).

1.5.2. Construction of a Library of huAbF46 Antibodies and Affinity for c-Met

The construction of antibody gene libraries through the introduction of random sequences was carried out using the primers synthesized in the same manner as in Reference Example 1.5.1. Two PCR products were obtained using a polynucleotide covering the scFV of huAbF46 as a template, and were subjected to overlap extension PCR to give scFv library genes for huAbF46 antibodies in which only desired CDRs were mutated. Libraries targeting each of the six CDRs prepared from the scFV library genes were constructed.

The affinity for c-Met of each library was compared to that of the wildtype. Most libraries were lower in affinity for c-Met, compared to the wild-type. The affinity for c-Met was retained in some mutants.

1.6. Selection of Antibody with Improved Affinity from Libraries

After maturation of the affinity of the constructed libraries for c-Met, the nucleotide sequence of scFv from each clone was analyzed. The nucleotide sequences thus obtained are summarized in Table 2 and were converted into IgG forms. Four antibodies which were respectively produced from clones L3-1, L3-2, L3-3, and L3-5 were used in the subsequent experiments.

TABLE 2 Library  Clone constructed CDR Sequence H11-4 CDR-H1 PEYYMS (SEQ ID NO: 22) YC151 CDR-H1 PDYYMS (SEQ ID NO: 23) YC193 CDR-H1 SDYYMS (SEQ ID NO: 24) YC244 CDR-H2 RNNANGNT (SEQ ID NO: 25) YC321 CDR-H2 RNKVNGYT (SEQ ID NO: 26) YC354 CDR-H3 DNWLSY (SEQ ID NO: 27) YC374 CDR-H3 DNWLTY (SEQ ID NO: 28) L1-1 CDR-L1 KSSHSLLASGNQNNYLA (SEQ ID NO: 29) L1-3 CDR-L1 KSSRSLLSSGNHKNYLA (SEQ ID NO: 30) L1-4 CDR-L1 KSSKSLLASGNQNNYLA (SEQ ID NO: 31) L1-12 CDR-L1 KSSRSLLASGNQNNYLA (SEQ ID NO: 32) L1-22 CDR-L1 KSSHSLLASGNQNNYLA (SEQ ID NO: 33) L2-9 CDR-L2 WASKRVS (SEQ ID NO: 34) L2-12 CDR-L2 WGSTRVS (SEQ ID NO: 35) L2-16 CDR-L2 WGSTRVP (SEQ ID NO: 36) L3-1 CDR-L3 QQSYSRPYT (SEQ ID NO: 13) L3-2 CDR-L3 GQSYSRPLT (SEQ ID NO: 14) L3-3 CDR-L3 AQSYSHPFS (SEQ ID NO: 15) L3-5 CDR-L3 QQSYSRPFT (SEQ ID NO: 16) L3-32 CDR-L3 QQSYSKPFT (SEQ ID NO: 37) 1.7. Conversion of Selected Antibodies into IgG

Respective polynucleotides encoding heavy chains of the four selected antibodies were designed to have the structure of “EcoRI-signal sequence-VH-NheI-CH-XhoI” (SEQ ID NO: 38). The heavy chains of huAbF46 antibodies were used as they were because their amino acids were not changed during affinity maturation. In the case of the hinge region, however, the U6-HC7 hinge (SEQ ID NO: 57) was employed instead of the hinge of human IgG1. Genes also were designed to have the structure of “EcoRI-signal sequence-VL-BsiWI-CL-XhoI” for the light chain. Polypeptides encoding light chain variable regions of the four antibodies which were selected after the affinity maturation were synthesized in BIONEER. Then, a DNA fragment having the heavy chain nucleotide sequence (SEQ ID NO: 38) and DNA fragments having the light chain nucleotide sequences (DNA fragment comprising L3-1-derived CDR-L3: SEQ ID NO: 58, DNA fragment comprising L3-2-derived CDR-L3: SEQ ID NO: 59, DNA fragment comprising L3-3-derived CDR-L3: SEQ ID NO: 60, and DNA fragment comprising L3-5-derived CDR-L3: SEQ ID NO: 61) were digested with EcoRI (NEB, R0101S) and XhoI (NEB, R0146S) before cloning into a vector from the pOptiVEC™-TOPO TA Cloning Kit enclosed in an OptiCHO™ Antibody Express Kit (Cat no. 12762-019, Invitrogen) and a vector from the pcDNA™3.3-TOPO TA Cloning Kit (Cat no. 8300-01), respectively, so as to construct recombinant vectors for expressing affinity-matured antibodies.

Each of the constructed vectors was amplified using Qiagen Maxiprep kit (Cat no. 12662), and a transient expression was performed using Freestyle™ MAX 293 Expression System (Invitrogen). 293 F cells were used for the expression and cultured in FreeStyle™ 293 Expression Medium in a suspension culture manner. At one day before the transient expression, the cells were provided in the concentration of 5×10⁵ cells/mL, and after 24 hours, when the cell number reached to 1×10⁶ cells/mL, the transient expression was performed. A transfection was performed by a liposomal reagent method using Freestyle™ MAX reagent (Invitrogen), wherein in a 15 mL tube, the DNA was provided in the mixture ratio of 1:1 (heavy chain DNA:light chain DNA) and mixed with 2 mL of OptiPro™ SFM (Invitrogen) (A). In another 15 mL tube, 100 μL of Freestyle™ MAX reagent and 2 mL of OptiPro™ SFM were mixed (B). This was followed by mixing (A) and (B) and incubating for 15 minutes. The obtained mixture was slowly mixed with the cells provided one day before the transient expression. After completing the transfection, the cells were incubated in 130 rpm incubator for 5 days under the conditions of 37° C., 80% humidity, and 8% CO₂.

After centrifugation, the supernatant was applied to AKTA prime fast protein liquid chromatography (GE Healthcare) to purify the antibody. In this regard, 100 mL of the supernatant was loaded at a flow rate of 5 mL/min to AKTA Prime fast protein liquid chromatography equipped with a Protein A column (GE Healthcare, 17-0405-03), followed by elution with an IgG elution buffer (Thermo Scientific, 21004). The buffer was exchanged with PBS to purify four affinity-matured antibodies (hereinafter referred to as “huAbF46-H4-A1 (L3-1 origin), huAbF46-H4-A2 (L3-2 origin), huAbF46-H4-A3 (L3-3 origin), and huAbF46-H4-A5 (L3-5 origin),” respectively).

1.8. Construction of Constant Region- and/or Hinge Region-Substituted huAbF46-H4-A1

Among the four antibodies selected in Reference Example 1.7, huAbF46-H4-A1 was found to be the highest in affinity for c-Met and the lowest in Akt phosphorylation and c-Met degradation degree. In the antibody, the hinge region, or the constant region and the hinge region, were substituted.

The antibody huAbF46-H4-A1 (U6-HC7) was composed of a heavy chain comprising (a) the heavy chain variable region of huAbF46-H4-A1, U6-HC7 hinge, and the constant region of human IgG1 constant region, and (b) a light chain comprising the light chain variable region of huAbF46-H4-A1 and human kappa constant region. The antibody huAbF46-H4-A1 (IgG2 hinge) was composed of (a) a heavy chain comprising a heavy chain variable region, a human IgG2 hinge region, and a human IgG1 constant region, and (b) a light chain comprising the light chain variable region of huAbF46-H4-A1 and a human kappa constant region. The antibody huAbF46-H4-A1 (IgG2 Fc) was composed of (a) the heavy chain variable region of huAbF46-H4-A1, a human IgG2 hinge region, and a human IgG2 constant region, and (b) a light chain comprising the light variable region of huAbF46-H4-A1 and a human kappa constant region. Hereupon, the histidine residue at position 36 on the human kappa constant region of the light chain was changed to tyrosine in all of the three antibodies to increase antibody production.

For use in constructing the three antibodies, a polynucleotide (SEQ ID NO: 63) encoding a polypeptide (SEQ ID NO: 62) composed of the heavy chain variable region of huAbF46-H4-A1, a U6-HC7 hinge region, and a human IgG1 constant region, a polynucleotide (SEQ ID NO: 65) encoding a polypeptide (SEQ ID NO: 64) composed of the heavy chain variable region of huAbF46-H4-A1, a human IgG2 hinge region, and a human IgG1 region, a polynucleotide (SEQ ID NO: 67) encoding a polypeptide (SEQ ID NO: 66) composed of the heavy chain variable region of huAbF46-H4-A1, a human IgG2 region, and a human IgG2 constant region, and a polynucleotide (SEQ ID NO: 69) encoding a polypeptide (SEQ ID NO: 68) composed of the light chain variable region of huAbF46-H4-A1, with a tyrosine residue instead of histidine at position 36, and a human kappa constant region were synthesized in BIONEER. Then, the DNA fragments having heavy chain nucleotide sequences were inserted into a vector from the pOptiVEC™-TOPO TA Cloning Kit enclosed in an OptiCHO™ Antibody Express Kit (Cat no. 12762-019, Invitrogen) while DNA fragments having light chain nucleotide sequences were inserted into a vector from the pcDNA™3.3-TOPO TA Cloning Kit (Cat no. 8300-01) so as to construct vectors for expressing the antibodies.

Each of the constructed vectors was amplified using Qiagen Maxiprep kit (Cat no. 12662), and a transient expression was performed using Freestyle™ MAX 293 Expression System (Invitrogen). 293 F cells were used for the expression and cultured in FreeStyle™ 293 Expression Medium in a suspension culture manner. At one day before the transient expression, the cells were provided in the concentration of 5×10⁵ cells/mL, and after 24 hours, when the cell number reached to 1×10⁶ cells/mL, the transient expression was performed. A transfection was performed by a liposomal reagent method using Freestyle™ MAX reagent (Invitrogen), wherein in a 15 mL tube, the DNA was provided in the mixture ratio of 1:1 (heavy chain DNA:light chain DNA) and mixed with 2 mL of OptiPro™ SFM (Iinvitrogen) (A). In another 15 mL tube, 100 μL of Freestyle™ MAX reagent and 2 mL of OptiPro™ SFM were mixed (B). This was followed by mixing (A) and (B) and incubating for 15 minutes. The obtained mixture was slowly mixed with the cells provided one day before the transient expression. After completing the transfection, the cells were incubated in 130 rpm incubator for 5 days under the conditions of 37° C., 80% humidity, and 8% CO₂.

After centrifugation, the supernatant was applied to AKTA prime fast protein liquid chromatography (GE Healthcare) to purify the antibody. In this regard, 100 mL of the supernatant was loaded at a flow rate of 5 mL/min to AKTA Prime fast protein liquid chromatography equipped with a Protein A column (GE Healthcare, 17-0405-03), followed by elution with IgG elution buffer (Thermo Scientific, 21004). The buffer was exchanged with PBS to finally purify three antibodies (huAbF46-H4-A1 (U6-HC7), huAbF46-H4-A1 (IgG2 hinge), and huAbF46-H4-A1 (IgG2 Fc)). Among the three antibodies, huAbF46-H4-A1 (U6-HC7) and huAbF46-H4-A1 (IgG2 Fc) were selected for the following examples, and respectively referred as anti-c-Met antibody L3-1Y U6-HC7 for huAbF46-H4-A1 (U6-HC7) and anti-c-Met antibody L3-1Y IgG2 for huAbF46-H4-A1 (IgG2 Fc).

Reference Example 2: Preparation of Anti-Her2 scFv

The sequence of a scFv antibody binding to Her2 was prepared on the basis of the sequence of Trastuzumab (HERCEPTIN) by inserting a peptide linker (G₄S)₃ (SEQ ID NO: 116) between the heavy chain variable region and the light chain variable region. Specifically, a (GGGGS)₃ (SEQ ID NO: 116) linker coding DNA sequence was added to the heavy chain variable region (SEQ ID NO: 109) coding DNA sequence (SEQ ID NO: 110) and the light chain variable region (SEQ ID NO: 111) coding DNA sequence (SEQ ID NO: 112) of the anti-Her2 antibody (HERCEPTIN) using an automatic gene synthesis (BIONEER Inc.) to synthesize a scFv coding DNA of the anti-Her2 antibody.

The thus obtained scFv of the anti-Her2 antibody (anti-Her2 scFv) was used to manufacture the following bispecific antibody.

<Amino acid sequence of anti-Her2  antibody heavy chain variable region> (SEQ ID NO: 109) EVQLVESGGGLVQPGGSLRLSCAASGFNIKDTYIHWVRQAPGKGLEWVAR IYPTNGYTRYADSVKGRFTISADTSKNTAYLQMNSLRAEDTAVYYCSRWG GDGFYAMDYWGQGTLVTVSS <Coding DNA sequence of anti-Her2  antibody heavy chain variable region> (SEQ ID NO: 110) gaagttcagctggtggagtctggcggtggcctggtgcagccagggggctc actccgtttgtcctgtgcagcttctggcttcaacattaaagacacctata tacactgggtgcgtcaggccccgggtaagggcctggaatgggttgcaagg atttatcctacgaatggttatactagatatgccgatagcgtcaagggccg tttcactataagcgcagacacatccaaaaacacagcctacctgcagatga acagcctgcgtgctgaggacactgccgtctattattgttctagatgggga ggggacggcttctatgctatggactactggggtcaaggaaccctggtcac cgtctcctcg <Amino acid sequence of anti-Her2  antibody light chain variable region> (SEQ ID NO: 111) DIQMTQSPSSLSASVGDRVTITCRASQDVNTAVAWYQQKPGKAPKLLIYS ASFLYSGVPSRFSGSRSGTDFTLTISSLQPEDFATYYCQQHYTTPPTFGQ GTKVEIKR <Coding DNA sequence of anti-Her2  antibody light chain variable region> (SEQ ID NO: 112) gatatccagatgacccagtccccgagctccctgtccgcctctgtgggcga tagggtcaccatcacctgccgtgccagtcaggatgtgaatactgctgtag cctggtatcaacagaaaccaggaaaagctccgaaactactgatttactcg gcatccttcctctactctggagtcccttctcgcttctctggttccagatc tgggacggatttcactctgaccatcagcagtctgcagccggaagacttcg caacttattactgtcagcaacattatactactcctcccacgttcggacag ggtaccaaggtggagatcaaacga

Example 1: Preparation of Bispecific Anti-c-Met/Anti-Her2 Antibody

The anti-Her2 scFv prepared in the Reference Example 2 was fused at the C-terminus of Fc of the anti cMet antibody L3-1Y-IgG2 (uAbF46-H4-A1(IgG2 Fc)) prepared in the Reference Example 1. The fusion procedures are as follows.

A DNA segment having a base sequence (SEQ ID NO: 66) corresponding to the heavy chain of the anti cMet antibody L3-1Y-IgG2 prepared in Reference Example 1 was inserted into a vector from the pcDNA™3.3-TOPO TA Cloning Kit (Cat no. 8300-01) which is included in OptiCHO™ Antibody Express Kit (Cat no. 12762-019) by Invitrogen Inc., and a DNA segment having a base sequence (SEQ ID NO: 68) corresponding to the light chain of the anti cMet antibody L3-1Y-IgG2 was inserted into a vector from the pOptiVEC™-TOPO TA Cloning Kit. Thereafter, the anti-Her2 scFv coding DNA prepared in Reference Example 2 was fused at the C-terminus of Fc of L3-1Y-IgG2 inserted into pcDNA™3.3 expression vector, using the coding DNA sequence of a peptide linker consisting of (GGGGS)₂ (SEQ ID NO: 113), to construct a vector for the expression of a bispecific antibody.

The constructed vectors were each amplified using Qiagen Maxiprep kit (Cat no. 12662 and their temporary expression proceeded using Freestyle™ MAX 293 Expression System (Invitrogen). 293 F cells, which were cultured in a suspension culture manner using FreeStyle™ 293 Expression Medium as a medium, were used. One day before the temporary expression, the cells were prepared at a concentration of 5×10⁵ cells/mL and after 24 hours, their temporary expression started when the number of the cells reached 1×10⁶ cells/mL. Transfection was performed by a liposomal reagent method using Freestyle™ MAX reagent (Invitrogen). DNA was prepared in a 15 mL tube in a ratio of heavy chain DNA:light chain DNA=3:2 and mixed with 2 mL of OptiPro™ SFM (Invitrogen) (A). 100 μL of Freestyle™ MAX reagent and 2 mL of OptiPro™ SFM were mixed in another 15 mL tube (B). After (A) and (B) were mixed and incubated for 15 min., the mixture solution was then slowly mixed into the cells which were prepared one day before. After the transfection was complete, the cells were cultured in a 37° C., 80% humidity, 8% CO₂, 130 rpm incubator for 5 days.

The cultured cells were centrifuged to obtain each 100 mL of supernatants, which were then purified using AKTA Prime fast protein liquid chromatography (GE Healthcare). The culture was added at a flow rate of 5 mL/min. to the AKTA Prime fast protein liquid chromatography installed with Protein A column (GE Healthcare, 17-0405-03) to perform elution using an IgG elution buffer (Thermo Scientific, 21004). The buffer was replaced by a PBS buffer to finally obtain a purified bispecific anti cMet/anti-Her2 antibody.

The thus prepared bispecific anti-c-Met/anti-Her2 antibody in which the anti-Her2 scFv is fused at the C-terminus of the anti-c-Met antibody L3-1Y-IgG2 was named MH2-01.

Example 2: Dual Binding of Bispecific Anti-c-Met/Anti-Her2 Antibody

Whether the anti-c-Met/anti-Her2 bispecific antibody prepared in the Example 1 is an antibody against two types of antigens (cMet/Her2) was determined using Biacore T100 (GE). An anti-6×His antibody (#MAB050, R&D Systems) was immobilized onto a CMS chip (#BR-1005-30, GE) using an amine coupling kit (#BR-1000-50, GE) according to the manufacturer's instructions. After the immobilization, c-Met-Fc (#358-MT/CF, R&D Systems) was injected thereto at a concentration of 15 μg/mL for 1 min. and then, the bispecific antibody MH2-01 prepared in Example 1 was injected at a concentration of 20 nM for 1 min. Thereafter, Her2-Fc (1129-ER, R&D Systems) was injected at 100 nM for 1 min.

The obtained results are shown in FIG. 2. The bispecific antibody MH2-01 prepared in the Example 1 bound to both c-Met and Her2 (see FIG. 2).

In addition, the affinities of the prepared bispecific anti-c-Met/anti-Her2 antibody toward two types of antigens (cMet/Her2) were each identified using BIACORE T100 (GE). A human Fab binder (GE Healthcare) was immobilized at the surface of a CMS chip (#BR-1005-30, GE) according to the manufacturer's specifications. About 90 to 120 Ru of MH2-01 was captured, and c-Met-Fc (#358-MT/CF, R&D Systems) or Her2-Fc (1129-ER, R&D Systems) were injected at various concentrations into the captured antibody. 10 mM Glycine-HCl (pH 1.5) solution was injected thereto to regenerate the surface. In order to measure affinity, the data obtained from this experiment was fitted using BIAevaluation software (GE Healthcare, BIACORE T100 evaluation software).

The obtained results are shown in FIG. 2 and Table 3.

TABLE 3 Antibody Antigen K_(D) (nM) k_(a) (1/Ms) k_(d) (1/s) MH2-01 cMet   0.14 6.6 × 10⁵   9.3 × 10⁻⁵ Her2 <0.01 1.2 × 10⁵ <1.1 × 10⁻⁵

As seen in FIG. 2 and Table 3, the bispecific antibody MH2-01 prepared in the Example 1 bound to both c-Met and Her2.

Reference Example 3: Preparation of Cell Lines

Cell lines to be used in the following examples to test the efficiency of the anti-c-Met/anti-Her2 bispecific antibody prepared in the Example 1 are EBC1, a lung cancer cell line, and MKN45, a stomach cancer cell line, which were purchased from ATCC.

Example 3: Suppression of Cancer Cell Proliferation by Anti-c-Met/Anti-Her2 Bispecific Antibody

Suppression effects on the proliferation of cancer cells of the anti-c-Met/anti-Her2 bispecific antibody prepared in the Example 1 were identified in the MKN45 stomach cancer cell line and EBC1 cells.

All the cell lines were cultured in a RPMI1640 medium (#11875-093, Gibco) to which 10% (v/v) FBS and 1% (v/v) Penicillin-Streptomycin were added, in 5% CO₂ and 37° C. conditions. For a cell proliferation assay, each cell line was subcultured at a concentration of 1×10⁴ cells/well in a 96-well plate, which was treated with the anti-c-Met/anti-Her2 bispecific antibody MH2-01 prepared in Example 1 in an amount of 5 μg/mL and cultured for 72 hours. A medium with no antibody added was used as a negative control, and commercially available Her2 inhibitor Herceptin (Roche) treatment group (marked as H), L3-1Y-IgG2 antibody 5 μg/mL treatment group prepared in Reference Example 1 (marked as L or L3-1Y), and co-treatment group (L+H) of L3-1Y-IgG2 antibody 5 μg/mL prepared in Reference Example 1 and Herceptin 5 μg/mL were each used as positive controls.

After cultivation, cell proliferation degrees were analyzed using Cell Counting Kit-8 assay (Dojindo Molecular Technologies, Gaithersburg, Md.) according to the manufacturer's instructions. In brief, after the cultivation for 72 hours, 10 μl of CCK8 solution was added to each well and after the additional cultivation for 2.5 hours, absorption degrees were read at 450 nm using a microplate reader.

The obtained results are shown in FIG. 3. As seen in FIG. 3, the anti-c-Met/anti-Her2 bispecific antibody MH2-01 showed remarkable increases in cell proliferation inhibitory effects in both cell lines, compared to the cases treated individually with the anti-c-Met antibody L3-1Y-IgG2 (L3-1Y) and the anti-Her2 antibody Herceptin. In particular, in the EBC-1 cells, the bispecific antibody MH2-01 showed excellent cell proliferation inhibitory effects, even compared to the co-treatment case of the anti-c-Met antibody L3-1Y-IgG2 (L+H).

Example 4: Her2 Activation Inhibitory Test of Anti-c-Met/Anti-Her2 Bispecific Antibody

The MKN45 cell line and EBC-1 cells were each treated with 5 μg/mL of Herceptin, 5 μg/mL of L3-1Y-IgG2 antibody (Reference Example 1), 5 μg/mL of MH2-01 (Example 1), and 5 μg/mL of L3-1Y-IgG2 and 5 μg/mL of Herceptin (co-treatment group), respectively for 24 hours.

Thereafter, the cells were lysed with COMPLETE Lysis-M lysis buffer (#04719956001, Roche) to collect cell lysates, which were then subject to SDS-PAGE electrophoresis.

After the electrophoresis, the proteins from the gels were transferred onto nitrocellulose membrane (#LC2006, Invitrogen), which was then blocked with a skim milk (5% in TBST (a mixture of Tris-Buffered Saline and TWEEN 20 (polysorbate 20))) at a room temperature for one hour. After blocking, for the first antibody reaction, the membrane was treated with a 1:2000 dilution of phospho c-Met antibody, anti phospho Her2 antibody, anti-Her2 antibody (all available from Cell Signaling Technology), and anti-c-Met antibody (Abcam) at a room temperature for two hours. After the first antibody reaction, the membrane was washed three times with PBS for 5 min. and then, it was treated with a 1:5000 dilution of the secondary antibody (Cell Signaling Technology) with horseradish peroxidase attached thereto against each first antibody at a room temperature for one hour. After the secondary antibody reaction, the membrane was washed three times with PBS for 5 min. and then sensitized with Enhanced chemiluminescence substrate (Thermo Scientific) to identify the degree of antigen-antibody reaction through IMAGEQUANT LAS system (GE Healthcare).

The obtained results are shown in FIG. 4. As seen in FIG. 4, when treated with the anti-c-Met/anti-Her2 bispecific antibody MH2-01, cMet was degraded and the activation of cMet was suppressed. Particularly, the degradation degree of Her2 was more excellent than the individual treatment of the anti-c-Met antibody L3-1Y-IgG2 or the anti-Her2 antibody Herceptin. This is to show that the anti-c-Met antibody and the anti-Her2 antibody have synergistic effects by forming a bispecific antibody together, compared to the sole Her2 inhibitor.

Example 5: Co-Localization of cMet and Her2 by Anti-c-Met/Anti-Her2 Bispecific Antibody

The MKN45 cell line and the EBC1 cell line were prepared in amounts of 4×10⁴ cells/well, respectively and an OE-33 cell line was prepared in an amount of 2×10⁴ cells/well, to which L3-1Y-IgG2 prepared in Reference Example 1 and Herceptin, and the anti-c-Met/anti-Her2 bispecific antibody MH2-01 prepared in Example 1 were each added individually or in combination to become the concentration of 1 μg/mL per well (in case of combination treatment, to become 1 μg/mL each) and treated at 37° C. for 4 hours. The cells were treated with 4% (v/v) formaldehyde for 15 min. to immobilize them on a plate, and washed three times with PBS. Thereafter, the cells were treated with a blocking buffer (0.5% triton x-100 and 5% donkey serum) at a room temperature for one hour and then treated with a 1:100 dilution of the first antibodies (cMet first antibody; #37-0100, Invitrogen, Her2 first antibody; #2165, Cell Signaling) against c-Met and Her2, respectively in amounts of 100 μL at 4° C. for 15 hours. After the cells were washed three time with PBS, they were treated with a 1:1000 dilution of the secondary antibodies (cMet secondary antibody; #A11001, Life Technology, Her2 secondary antibody; #A21244, Life Technology) against c-Met and Her2, respectively in amounts of 100 μL at a room temperature for 1 hour and washed three times with PBS to prepare a plate as a mounting medium (#H-1200, Vector). The prepared cells were observed with a confocal microscope (Zeiss, LSM710).

The obtained results are shown in FIG. 5 (MKN45 stomach cancer cell line), FIG. 6 (EBC-1 lung cancer cell line), and FIG. 7 (OE-33 esophagus cancer cell line). As seen in FIG. 5, FIG. 6, and FIG. 7, in the case of the sole treatment of Herceptin, Her2 was still located at cell membranes; even in the case of the co-treatment of L3-1Y and Herceptin, only c-Met migrated inside the cells and most of Her2 was located at the cell membranes; however, in the case of the treatment of the anti-c-Met/anti-Her2 bispecific antibody MH2-01, both c-Met and Her2 migrated inside the cells. This result demonstrates that the double antibody MI-12-01 against c-Met/Her2 can increase anticancer effects by the internalization of cMet and Her2 into the cells at the same time.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. 

What is claimed is:
 1. An anti-c-Met/anti-Her2 bispecific antibody comprising (a) an anti-c-Met antibody in an IgG form comprising six complementarity determining regions (CDRs), linked to (b) an antigen-binding fragment of an anti-Her2 antibody comprising six complementarity determining regions, wherein the anti-c-Met antibody comprises: (i) a heavy chain variable region comprising a CDR-H1 comprising the amino acid sequence of SEQ ID NO: 1; a CDR-H2 comprising the amino acid sequence of SEQ ID NO: 2 and a CDR-H3 comprising the amino acid sequence of SEQ ID NO: 3; and (ii) a light chain variable region comprising a CDR-L1 comprising the amino acid sequence of SEQ ID NO: 10; a CDR-L2 comprising the amino acid sequence of SEQ ID NO: 11; and a CDR-L3 comprising the amino acid sequence of SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, or SEQ ID NO:
 16. 2. The anti-c-Met/anti-Her2 bispecific antibody according to claim 1, wherein the antigen-binding fragment is an scFv, (scFv)2, Fab, Fab′ or F(ab′)₂.
 3. The anti-c-Met/anti-Her2 bispecific antibody according to claim 1, wherein the anti-c-Met antibody comprises: (i) a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 17, and (ii) a light chain variable region comprising the amino acid sequence of SEQ ID NO: 114, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, or SEQ ID NO:
 21. 4. The anti-c-Met/anti-Her2 bispecific antibody according to claim 1, wherein the anti-c-Met antibody comprises: (i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 62, the amino acid sequence from positions 18 to 462 of SEQ ID NO: 62, the amino acid sequence of SEQ ID NO: 64, the amino acid sequence from positions 18 to 461 of SEQ ID NO: 64, the amino acid sequence of SEQ ID NO: 66, or the amino acid sequence from positions 18 to 460 of SEQ ID NO: 66; and (ii) a light chain comprising the amino acid sequence of SEQ ID NO: 68, the amino acid sequence from positions 21 to 240 of SEQ ID NO: 68, the amino acid sequence of SEQ ID NO: 70, the amino acid sequence from positions 21 to 240 of SEQ ID NO:
 70. 5. The anti-c-Met/anti-Her2 bispecific antibody according to claim 1, wherein the anti-c-Met antibody comprises a heavy chain comprising the amino acid sequence of SEQ ID NO: 66 or the amino acid sequence from positions 18 to 460 of SEQ ID NO: 66, and a light chain comprising the amino acid sequence of SEQ ID NO: 68 or the amino acid sequence from positions 21 to 240 of SEQ ID NO:
 68. 6. The anti-c-Met/anti-Her2 bispecific antibody according to claim 1, wherein the anti-Her2 antigen binding fragment is an antigen binding fragment from Trastuzumab or Pertuzumab.
 7. The anti-c-Met/anti-Her2 bispecific antibody according to claim 1, wherein the antigen-binding fragment of the anti-Her2 antibody is covalently linked to the C-terminus of the anti-c-Met antibody.
 8. The anti-c-Met/anti-Her2 bispecific antibody according to claim 7, wherein the antigen-binding fragment of the anti-Her2 antibody comprises a heavy chain variable region comprising the sequence of SEQ ID NO: 109 and a light chain variable region comprising the sequence of SEQ ID NO:
 111. 9. A pharmaceutical composition comprising the anti-c-Met/anti-Her2 bispecific antibody according to claim 1 and a pharmaceutically acceptable carrier.
 10. A method of treatment of a cancer, comprising administering the anti-c-Met/anti-Her2 bispecific antibody of claim 1 to a patient in need thereof. 